US6519028B2 - Optical characteristic measuring apparatus, the method thereof and recording medium - Google Patents

Optical characteristic measuring apparatus, the method thereof and recording medium Download PDF

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US6519028B2
US6519028B2 US09/900,968 US90096801A US6519028B2 US 6519028 B2 US6519028 B2 US 6519028B2 US 90096801 A US90096801 A US 90096801A US 6519028 B2 US6519028 B2 US 6519028B2
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wavelength
waveform
light
variable
identification
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US20020024655A1 (en
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Eiji Kimura
Motoki Imamura
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Advantest Corp
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Advantest Corp
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
    • G01M11/335—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face using two or more input wavelengths
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
    • G01M11/333—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face using modulated input signals
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/30—Testing of optical devices, constituted by fibre optics or optical waveguides
    • G01M11/33—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face
    • G01M11/338—Testing of optical devices, constituted by fibre optics or optical waveguides with a light emitter being disposed at one fibre or waveguide end-face, and a light receiver at the other end-face by measuring dispersion other than PMD, e.g. chromatic dispersion

Definitions

  • the present invention relates to the measurement of chromatic dispersion characteristics of a DUT (Device Under Test) such as an optical fiber, and in particular to the measurement which can obtain synchronization of a variable-wavelength light source and a phase comparator with a high precision, by providing the variable-wavelength light source at one end of the DUT and the phase comparator at the other end of the DUT.
  • a DUT Device Under Test
  • FIG. 8 The construction of a measuring system which measures chromatic dispersion characteristics of the DUT such as an optical fiber is shown in FIG. 8.
  • a light source system 100 is connected to one end of an optical fiber 300 and a measuring system 200 is connected to the other end of the optical fiber 300 .
  • the light source system 100 has a variable-wavelength light source 102 and an optical modulator 104 .
  • the measuring system 200 includes a photoelectric (OLE) converter 202 and a phase comparator 204 .
  • OLED photoelectric
  • variable-wavelength light source 102 changes the wavelength ⁇ x of generated light.
  • the light generated by the variable-wavelength light source 102 is modulated by a modulation frequency Fm in the optical modulator 104 and inputted to the optical fiber 300 .
  • the light transmitted through the optical fiber 300 is converted into an electric signal in the photoelectric (OLE) converter 202 .
  • the phase comparator 204 measures a phase difference between a phase of an electric signal and a phase which is to be a reference with respect to the electric signal.
  • Group delay (GD) can be calculated from the phase difference and modulation frequency Fm.
  • Chromatic dispersion (CD) can be calculated by differentiating group delay by the wavelength of the group delay.
  • the frequencies of ⁇ x and Fm are communicated to the measuring system 200 .
  • FIGS. 9 ( a )- 9 ( b ) Waveforms of light generated by the light source system 100 and light received by the measuring system 200 are schematically shown in FIGS. 9 ( a )- 9 ( b ).
  • FIG. 9 ( a ) shows the waveform of light generated by the light source system 100 .
  • FIG. 9 ( b ) shows the waveform of light received by the measuring system 200 .
  • Time delay t 0 added to the light generated by the light source system 100 makes a light to be received by the measuring system 200 .
  • the drawing shows as if there is no discrepancy of phases between the light generated by the light source system 100 and the light received by the measuring system 200 .
  • t 0 is increased as the length of optical fiber increases.
  • the length of optical fiber in a submarine cable and the like is about 10000 km, and to is up to 50 ms.
  • the time delay t 0 is generated in the light received by the measuring system 200 . Therefore, if the light source system 100 changes a wavelength directly after a light of a certain wavelength is generated, it becomes impossible to know ⁇ x (wavelength of light generated by the variable wavelength light source 102 ) corresponding to the light received by the measuring system 200 .
  • FIG. 10 shows a method for changing the wavelength of light generated by the light source system 100 . Firstly, a light, the wavelength of which is ⁇ 0 from time 0 to t 1 , ⁇ 1 from time t 1 to 2t 1 , and so on, is generated. That is, the wavelength of light is changed in a step form.
  • variable-wavelength light source 102 cannot perform measurement of wavelength while continuously changing the waveform, even if it had a function which renders it possible to continuously sweep the wavelength. This is because it is impossible to exactly known ⁇ x (wavelength of light generated by the variable-wavelength light source 102 ) corresponding to the light received by the measuring system 200 . That is, it is impossible to obtain a synchronization of light source system 100 and measuring system 200 . Therefore, the wavelength of light is changed in the step form and measured.
  • the time required for measuring is longer than that required in the case of continuously sweeping the wavelength.
  • wavelength changing values ⁇ 2- ⁇ 1, ⁇ 1- ⁇ 0, . . . ) are not taken so high to a certain extent, the measuring time takes too long. Therefore, it is impossible to improve the resolution of wavelength.
  • the object of the present invention is to provide a technique for measuring characteristics, such as chromatic dispersion and the like, by making it possible to continuously sweep the wavelength of light source.
  • an apparatus for measuring optical characteristics of a device-under-test which transmits light includes: a variable-wavelength light source for generating a variable-wavelength light, the wavelength of which is variable, having an identification waveform at the time when the wavelength is changing, wherein the identification waveform is distinguishable from a normal waveform before and after the time when the wavelength is changing; an optical modulation unit for modulating the variable-wavelength light at a predetermined frequency and then inputting it to the device-under-test; and an identification waveform detection unit for detecting the identification waveform in the transmitted light transmitted through the device-under-test.
  • the time when the identification waveform detection unit detects the identification waveform is the time when the waveform starts to change, it is possible to obtain a synchronization between an incidence side and an exit side of a device-under-test using the time when the identification waveform is detected. Accordingly, it is possible to obtain the synchronization between an incidence side and an exit side of a device-under-test, even if the wavelength of light source is continuously swept.
  • an apparatus for measuring optical characteristics of a device-under-test which transmits light includes: a variable-wavelength light source for generating a variable-wavelength light, the wavelength of which is variable, having an identification waveform at the time when the wavelength is changing, wherein the identification waveform is distinguishable from a normal waveform before and after the time when the wavelength is changing; and an optical modulation unit for modulating the variable-wavelength light at a predetermined frequency and then inputting it to the device-under-test.
  • an apparatus for measuring optical characteristics of a device-under-test which transmits light includes: an identification waveform detection unit for detecting identification waveform in a transmitted light which is an incident light transmitted through the device-under-test, wherein the incident light is a variable-wavelength light, the wavelength of which is variable, having in the form of the identification waveform at the time when the wavelength is changing, and wherein the identification waveform is distinguishable from a normal waveform before and after the time when the wavelength is changing.
  • the present invention described above is an apparatus for measuring optical characteristics, wherein the identification waveform is a waveform different from the normal waveform in wavelength.
  • the present invention described above is an apparatus for measuring optical characteristics, wherein the identification waveform is a waveform different from the normal waveform in output condition.
  • the output condition corresponds to ON or OFF of the light source.
  • the present invention described above is an apparatus for measuring optical characteristics, wherein the device-under-test includes a first optical line that transmits light only in one direction, and a second optical line that transmits light only in a direction opposite to the one direction, and wherein the variable-wavelength light source and optical modulation unit are connected to the incidence side of the first optical line and the identification waveform detection unit is connected to the exit side of the second optical line.
  • an apparatus for measuring optical characteristics further includes: a phase measuring unit for measuring the phase of the transmitted light by correlating it with the wavelength of the variable-wavelength using the time at which the identification waveform detection unit detects the identification waveform; and a characteristic calculation unit for calculating group delay characteristics or dispersion characteristics of device-under-test using the phase of the transmitted light.
  • a method for measuring optical characteristics of a device-under-test which transmits light includes: a variable-wavelength light generating step for generating a variable wavelength light, the wavelength of which is variable, having an identification waveform at the time when the wavelength is changing, wherein the identification waveform is distinguishable from a normal waveform before and after the time when the wavelength is changing; an optical modulation step for modulating the variable-wavelength light at a predetermined frequency and then inputting it to the device-under-test; and an identification waveform detection step for detecting the identification waveform in the transmitted light transmitted through the device-under-test.
  • a method for measuring optical characteristics of a device-under-test which transmits light includes: a variable-wavelength light generating step for generating a variable- wavelength light, the wavelength of which is variable, having an identification waveform at the time when the wavelength is changing, wherein the identification waveform is distinguishable from a normal waveform before and after the time when the wavelength is changing; and an optical modulation step for modulating the variable-wavelength light to a predetermined frequency and then inputting it to the device-under-test.
  • a method for measuring optical characteristics of a device-under-test which transmits light includes: an identification waveform detection step for detecting an identification waveform in a transmitted light which is an incident light transmitted through the device-under-test, wherein the incident light is a variable-wavelength light, the wavelength of which is variable, having in the form of the identification waveform at the time when the wavelength is changing, and wherein the identification waveform is distinguishable from a norinall waveform before and after the time when the wavelength is changing.
  • the present invention is a computer-readable medium having a program of instructions for execution by the computer to perform an optical characteristic measuring process for measuring a characteristic of a device-under-test which transmits light, the optical characteristic measuring process including: a variable-wavelength light generating processing for generating a variable-wavelength light, the wavelength of which is variable, having an identification waveform at the time when the wavelength is changing, wherein the identification waveform is distinguishable from a normal waveform before and, after the time when the wavelength is changing; an optical modulation processing for modulating the variable-wavelength light at a predetermined frequency and then inputting it to the device-under-test; and an identification waveform detection processing for detecting the identification waveform in the transmitted light transmitted through the device-under-test.
  • the present invention is a computer-readable medium having a program of instructions for execution by the computer to perform an optical characteristic measuring process for measuring a characteristic of a device-under-test which transmits light, the optical characteristic measuring process including: a variable-wavelength light generating processing for generating a variable-wavelength light, the wavelength of which is variable, having an identification waveform at the time when the wavelength is changing, wherein the identification waveform is distinguishable from a normal waveform before and after the time when the wavelength is changing; and an optical modulation processing for modulating the variable wavelength light at a predetermined frequency and then inputting it to the device under-test.
  • the present invention is a computer-readable medium having a program of instructions for execution by the computer to perform an optical characteristic measuring process for measuring a characteristic of a device-under-test which transmits light, the optical characteristic measuring process including: an identification waveform detection processing for detecting identification waveform in a transmitted light which is an incident light transmitted through the device-under-test, wherein the incident light is a variable-wavelength light, the wavelength of which is variable, having in the form of the identification waveform at the time when the wavelength is changing, and wherein the identification waveform is distinguishable from a normal waveform before and after the time when the wavelength is changing.
  • the present invention is an apparatus for measuring optical characteristics, wherein the identification waveform is a waveform different from the normal waveform in wavelength.
  • the present invention is an apparatus for measuring optical characteristics, wherein the identification waveform is a waveform different from the normal waveform in output condition.
  • the present invention is an apparatus for measuring optical characteristics, further including: a phase measuring unit for measuring the phase of the transmitted light by correlating it with the wavelength of the variable-wavelength using the time at which the identification waveform detection unit detects the identification waveform; and a characteristic calculation unit for calculating group delay characteristics or dispersion characteristics of device-under-test using the phase of the transmitted light.
  • FIG. 1 is a block diagram showing the construction of an optical characteristic measuring apparatus according to the first embodiment of the present invention
  • FIGS. 2 ( a )- 2 ( d ) show the waveforms and wavelengths of variable-wavelength light source 12 ;
  • FIGS. 3 ( a )- 3 ( c ) are flowcharts showing the operation of the first embodiment of the present invention, in which FIG. 3 ( a ) shows the operation of light source system ( 10 ), FIG. 3 ( b ) shows the operation of characteristic measuring system 20 , and FIG. 3 ( c ) shows the operation of identification waveform detection section 24 ;
  • FIGS. 4 ( a )- 4 ( b ) show waveforms of incident light (FIG. 4 ( a )) and transmitted light (FIG. 4 ( b ));
  • FIGS. 5 ( a )- 5 ( b ) show waveforms of incident light (FIG. 5 ( a )) and transmitted light (FIG. 5 ( b )) in the second embodiment;
  • FIGS. 6 ( a )- 6 ( b ) show waveforms of incident light (FIG. 6 ( a )) and transmitted light (FIG. 6 ( b )) in the second embodiment;
  • FIG. 7 is a block diagram showing the optical characteristic measuring apparatus according to the third embodiment of the present invention.
  • FIG. 8 is a block diagram showing a construction of measuring system for measuring chromatic dispersion characteristics of the DUT such as an optical fiber in the prior art
  • FIGS. 9 ( a )- 9 ( b ) show waveforms of light produced by the optical light source system 100 (FIG. 9 ( a )) and of light received by the measuring system 200 (FIG. 9 ( b )) in the prior art;
  • FIG. 10 shows a method for changing the wavelength of light generated by the light source system 100 in the prior art.
  • FIG. 1 is a block diagram showing the construction of an optical characteristic measuring apparatus according to the first embodiment of the present invention.
  • the optical characteristic measuring apparatus includes a light source system 10 connected to one end of an optical fiber 30 and a characteristic measuring system 20 connected the other end of the optical fiber 30 .
  • the light source system 10 comprises a variable-wavelength light source 12 and an optical modulator 14 .
  • the variable-wavelength light source 12 has an identification waveform at the time when the wavelength starts to change (t 0 ), wherein the identification waveform is distinguishable from a normal waveform before and after that time. The normal waveform and the identification waveform will be explained with reference to FIGS. 2 ( b ) to 2 ( d ).
  • the normal waveform is, for example, a sine wave of a wavelength ⁇ 0.
  • FIG. 2 ( c ) shows a waveform that serves as a basis for generating an identification waveform. For example, it is a sine wave of wavelength ⁇ ′, in which only quarter-wavelength portion is present. In addition, it is desired that ⁇ ′ is much smaller than ⁇ 0.
  • FIG. 2 ( d ) is a waveform of the variable-wavelength light source 12 in the time at which the wavelengths starts to change (t ⁇ 0). It is a waveform of multi-wavelength which is the sum of waveforms of FIGS. 2 ( b ) and ( c ).
  • the optical modulator 14 modulates the variable wavelength light to a frequency Fm.
  • the optical modulator 14 may include lithium/niobate (LN). Also, it may not include LN if it can modulate a light.
  • the light exited from the optical modulator 14 is inputted to an optical fiber line 30 .
  • the light inputted to the optical fiber 30 transmits through the optical fiber 30 .
  • the light transmitted through the optical fiber 30 is referred to as transmitted light.
  • the characteristic measuring system 20 comprises a photoelectric converter 22 , an identification waveform detection section 24 , a phase comparator 26 , and a characteristic calculation section 28 .
  • the photoelectric converter 22 converts the transmitted light into an electrical signal.
  • the identification wave detection section 24 detects an identification waveform from the electrical signal.
  • the identification waveform detection section 24 also measures the time t 0 at which the identification waveform appears in the transmitted light.
  • the phase comparator 26 measures the phase of the transmitted light by correlating it with the wavelength of the variable-wavelength light using the time t 0 at which the identification waveform appears in the transmitted light.
  • the phase difference is calculated by comparing the phase of the transmitted light with a phase at the time when the incident light having a reference wavelength is inputted.
  • the transmitted light has a time delay equal to the time t 0 as compared to the incident light
  • the transmitted light corresponding to the incident light at an optical time t (wavelength, ⁇ x (I)) will be the transmitted light at the time t+t 0 .
  • the phase of transmitted light at the time t+t 0 will be corresponding to the wavelength ⁇ x (t) of incident light.
  • the phase difference is calculated by comparing the phase of transmitted light with a phase at the time when the incident light having a reference wavelength is inputted.
  • the characteristic calculation section 28 records the phase difference measured by the phase comparator 26 and calculates either group delay characteristics or chromatic dispersion characteristics of the optical fiber 30 based on the phase.
  • the group delay characteristics can be calculated from the relationship between the phase difference measured by the phase comparator 26 and the modulated frequency Fm.
  • the chromatic dispersion characteristics can be calculated by differentiating the group delay characteristics by the wavelength of the group delay.
  • FIG. 3 ( a ) and FIG. 3 ( b ) respectively show operations of the light source system 10 and the characteristic measuring system 20 .
  • the wavelength Ax of variable-wavelength light is changed with reference to FIG. 3 ( a ) (S 10 ).
  • the optical modulator 14 modulates the variable-wavelength light (S 12 ).
  • the modulated light is inputted to the optical fiber 30 . And, it returns to the changing (sweeping) of the wavelength ⁇ x of the variable-wavelength light (S 10 ).
  • the process is terminated by cutting-off a power source (S 13 ).
  • the incident light is transmitted through the optical fiber 30 .
  • the light transmitted through the optical fiber 30 is referred to as the transmitted light.
  • the characteristic measuring system 20 determines whether the characteristic measuring system 20 has received the transmitted light (S 14 ). If received (S 14 , Yes), the transmitted light is subjected to photoelectric conversion to an electrical signal by the photoelectric converter 22 (S 16 ). The electrical signal is sent to the identification waveform detection section 24 and the identification waveform is detected from the electrical signal (S 17 ). The identification waveform detection section 24 also measures time t 0 at which the identification waveform appears in the transmitted light.
  • FIG. 4 ( a ) is a waveform of the incident light.
  • FIG. 4 ( b ) is a waveform of the exited light.
  • the t 0 is a time delay of transmitted light in relation to the incident light. Assuming that the amplitude of normal waveform in the vicinity of t 0 is 1, the maximum amplitude value of identification waveform is two (2).
  • FIG. 4 ( a ) is a waveform of the incident light.
  • the identification waveform detection section 24 determines whether or not the value of the electrical signal exceeds 1 (S 17 a ). Here, if the value has not exceeded 1 (S 17 a, No), the process continuously returns to the monitoring of the electrical signal value (S 17 a ), because the incident light, in which wavelength was swept, has not yet been received. If the value has exceeded 1 (S 17 a, Yes), the time at which the value has exceeded 1 is recorded as the time delay t 0 (S 17 b ), because the time at which the value has exceeded 1 is t 0 .
  • the phase comparator 26 measures the phase of transmitted light by correlating it with the wavelength of the variable-wavelength light using the time to, at which the identification waveform appears in the transmitted light (S 18 ). And, the phase difference is calculated by comparing the phase of the transmitted light with a phase at the time when the incident light having a reference wavelength is inputted.
  • the transmitted light has a time delay equal to the time t 0 as compared to the incident light
  • the transmitted light corresponding to the incident light at an optional time t (wavelength ⁇ x (t)) will be the transmitted light at the time t+t 0 .
  • the phase of transmitted light at the time t+t 0 will be corresponding to the wavelength ⁇ x (t) of incident light.
  • the phase difference is calculated by comparing the phase of transmitted light with a phase at the time when the incident light having a reference wavelength is inputted.
  • phase difference measured by being correlated with the wavelength ⁇ x (t) of incident light is sent to the characteristic calculation section 28 and recorded therein (S 20 ).
  • the characteristic calculation section 28 calculates either group delay characteristics or chromatic dispersion characteristics of the optical fiber 30 based on the recorded phase difference (S 22 ).
  • the group delay characteristics can be calculated from the relationship between the phase difference measured by the phase comparator 26 and the modulated frequency Fm.
  • the chromatic dispersion characteristics can be calculated by differentiating the group delay characteristics by the wavelength of the group delay.
  • the first embodiment it is possible to measure the phase difference by correlating it with the wavelength ⁇ x (t) of incident light and the group delay characteristics can be calculated based on the phase difference. Therefore, it is possible to continuously change the wavelength, and measuring time is rapidly reduced rather than changing the wavelength in the step form. Furthermore, the precision in wavelength axis of measurement result is improved because the time of variable-wavelength can be exactly specified. Also, the resolution of wavelength is improved, because the wavelength is continuously swept.
  • the first embodiment uses the optical fiber 30 as the device-under-test, it is also especially effective in measuring a line that has complicated characteristics using an optical filter and the like.
  • An optical characteristic measuring apparatus is different from the first embodiment in that it produces the identification waveform by switching output conditions, so to speak, by switching a variable wavelength light source 12 ON and OFF.
  • the identification waveforms of incident light will be explained.
  • FIG. 5 ( a ) is a waveform of the incident light.
  • FIG. 5 ( b ) is a waveform of the transmitted light. Because the value of the electrical signal is set to zero (0) with respect to the time delay to, the time when the value of the electrical signal is zero may be recorded as t 0 .
  • FIG. 6 ( a ) is a waveform of the incident light.
  • FIG. 6 ( b ) is a waveform of the transmitted light. Because the value of the electrical signal is set to 1 with respect to the time delay t 0 , the time when the value of the electrical signal is one may be recorded as t 0 .
  • FIG. 7 is a block diagram schematically showing the construction of an optical characteristic measuring apparatus according to the third embodiment.
  • Optical characteristic measuring apparatuses 52 and 54 according to the third embodiment comprise a light source system 10 and a characteristic measuring system 20 , respectively.
  • the internal constructions of light source systems 10 and characteristic measuring systems 20 are same as those of first embodiment and thus, the detailed illustration thereof has been omitted.
  • a one-fiber pair 40 comprises an optical fiber line 42 and an optical fiber line 44 .
  • the optical fiber line 42 comprises an optical fiber 42 a and an optical amplifier 42 b that is connected on the route of the optical fiber 42 a to amplify a light.
  • the optical fiber line 42 transmits the light in the right direction.
  • the optical fiber line 44 comprises an optical fiber 44 a and an optical amplifier 44 b that is connected on the route of the optical fiber 44 a to amplify a light.
  • the optical fiber line 44 transmits the light in the left direction.
  • the light source system 10 of optical characteristic measuring apparatus 52 is connected to the incidence side of the optical fiber line 42 (first optical line).
  • the characteristic measuring system 20 of optical characteristic measuring apparatus 52 is connected to the exit side of the optical fiber line 44 (second optical line).
  • the light source system 10 of optical characteristic measuring apparatus 54 is connected to the incidence side of the optical fiber line 44 (first optical line).
  • the characteristic measuring system 20 of optical characteristic measuring apparatus 54 is connected to the exit side of the optical fiber line 42 (second optical line).
  • third embodiment is same as that of first embodiment.
  • the third embodiment it is possible to measure both of the optical fiber lines 42 and 44 of one-fiber pair 40 .
  • this embodiment can be implemented as follows.
  • a media reading apparatus of a computer comprising a CPU, a hard disk, and a media reading apparatus (floppy disk, CD-ROM and the like) is rendered to read a media recorded with a program for implementing each of the above-mentioned sections and installs it in the hard disk.
  • a media reading apparatus floppy disk, CD-ROM and the like
  • the time when the identification waveform detection means detects the identification waveforms is the time when the waveform starts to change, it is possible to obtain a synchronization of incidence side and exit side of a device-under-test using the time at which the identification waveform is detected. Accordingly, it is possible to obtain the synchronization of the incidence side and the exit side of a device-under-test even if the wavelength of a light source was continuously swept.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Optics & Photonics (AREA)
  • Analytical Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Dispersion Chemistry (AREA)
  • Testing Of Optical Devices Or Fibers (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
US09/900,968 2000-07-10 2001-07-10 Optical characteristic measuring apparatus, the method thereof and recording medium Expired - Fee Related US6519028B2 (en)

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JP2000208845A JP2002022613A (ja) 2000-07-10 2000-07-10 光特性測定装置、方法、記録媒体
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US20050179889A1 (en) * 2002-04-09 2005-08-18 Marco Schiano Apparatus and method for measuring chromatic dispersion by variable wavelength

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WO2009040144A1 (fr) * 2007-09-28 2009-04-02 Telefonaktiebolaget Lm Ericsson (Publ) Amplificateur optique

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US20050179889A1 (en) * 2002-04-09 2005-08-18 Marco Schiano Apparatus and method for measuring chromatic dispersion by variable wavelength
US7106427B2 (en) * 2002-04-09 2006-09-12 Telecom Italia S.P.A Apparatus and method for measuring chromatic dispersion by variable wavelength

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FR2811755A1 (fr) 2002-01-18
CA2352687C (fr) 2005-08-23
US20020024655A1 (en) 2002-02-28
DE10133323A1 (de) 2002-04-11
CA2352687A1 (fr) 2002-01-10
JP2002022613A (ja) 2002-01-23
FR2811755B1 (fr) 2005-01-28
GB2369433B (en) 2002-11-13
GB0116572D0 (en) 2001-08-29
GB2369433A (en) 2002-05-29

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